Obama drove excitement, but blacks voting over 90% Dem is nothing new. Conservatives want live babies so they can raise them to be dead soldiers. - George Carlin
Of course, young voters have all or most of their adult life with Bush as President, so the more McCain played to the Republican base, the more he ensured Obama's dominance of the youth vote.
And in Ohio at least, while the growth in Democratic share of the Black or Hispanic vote on their own were not enough for the margin of victory, AFAIU, the growth in the Democratic share of the youth vote was sufficient on its own to flip the result from 2004. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.